Turbulence Penetration

8/10/2019 Turbulence Penetration

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EXERCISE 142

TURBULENCEPENETRATIONPROCEDURES

CO-ORDINATEDBRIEFING


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Turbulence Penetration Procedures Co-ordinated Briefing, Issue 1 Page 2 of 18This is an internal publication for Qantas Flight Crew 30 January, 2001

This Page Intentionally LeftBlank


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Table of Contents

1. Introduction Page 4

2. Turbulence Reporting Page 5

3. Anticipated Turbulence Page 5

4. Unanticipated Turbulence Page 5

5. Turbulent Air Penetration Page 5

6. Turbulence Page 5

7. FMC Page 6

8. Rules of Thumb for avoiding or minimising encounters with CAT Page 6

9. FAA Advisory Circular 00-30A

9.1 Introduction Page 6

9.2 Purpose Page 6

9.3 Background Pages 6,7

9.4 Discussion Pages 7,8,9

9.5 Recommendations Page 9

9.6 Summary Page 9,10

10. List of Manual References

10.1 List of Manual References 744 Page 11




11. Appendix 1 Pages 15,16

Rules of Thumb to assist in avoiding or minimising encounter with

clear air turbulence.

12. Bibliography Page 17

Disclaimer:All information contained in this document is accurate at time of printing.For the latest version of information please refer to your fleet specific manuals.


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1. INTRODUCTION

Welcome to the first of our series of Standard Briefings.

A recent Flight Training initiative is the introduction of Standard Briefings for Recurrent

Training exercises. The aim is to ensure that Pilots and Instructors from all fleets are given

the same briefing information for each exercise. These briefings will ensure that crew

receive the required information pertaining to the topic, and that Flight Training complies with

the Quality Assurance standards required by the ISO9002 accreditation.

Each Standard Briefing includes; an outline of the key areas related to the topic, a list of

applicable reference material and related material from industry sources. Please note that

the information contained in this document is accurate ONLYat the time of printing.

Turbulence Penetration Procedures for Exercise 142 is the first Standard Briefing to be

released under this new development.

In conjunction with this guide you are encouraged to conduct your own research to increase

your depth of knowledge and understanding of the topic under discussion.

Flight Training is continually striving to improve the training process. Feedback forms areavailable at time of briefing and any suggestions for improvement are greatly appreciated .


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2. TURBULENCE REPORTING (FAM 20(S) 4)

Light, moderate, severe, extreme.

From the Turbulence Reporting Criteria Table understand the aircraft reaction and

reaction inside aircraft to the various intensities of turbulence.

3. ANTICIPATED TURBULENCE (FAM CABIN MANAGEMENT)

Liase with CSM

PA

Cabin Crew prioritise duties

Seat Belt sign ON

PA

Call Back

4. UNANTICIPATED TURBULENCE (FAM CABIN MANAGEMENT)

Seat Belt sign ON

PA

Call back if situation allows

Note: In both cases, Flight Crew should be aware of Cabin Crew duties.

5. TURBULENT AIR PENETRATION - FCTM 1.18 - B737- FCTM 01.10 - B767- FCTM 02.20.03 - B747- FCTM 1.31 - B744

This section of the FCTM details the Turbulent Air Penetration techniques.

Note that if severe Turbulence can not be avoided, an increased buffet margin is

recommended. This can be obtained by descending approximately 4,000 feet below

optimum altitude.

6. TURBULENCE - OPERATIONS MANUAL SP.16.15 - B737- OPERATIONS MANUAL SP.16.8 - B767- OPERATIONS MANUAL 02.30.16 - B747- OPERATIONS MANUAL SP.16.15 - B744

This section of the Operations Manual details the Turbulence procedure.

Note that thrust is set as required for the phase of flight. Once set, change thrust

setting only if required to modify an unacceptable speed trend.


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7. FMC

The FMC CRZ page displays proper N1 for Turbulence Penetration (Turb N1), during cruise.

This value is for reference only. It is not commanded to the autothrottle. For the B747 refer

to the table in the Performance Manual, Limitations section.

8. RULES OF THUMB FOR AVOIDING OR MINIMISING ENCOUNTERS WITH

CAT

FAA Advisory Circular 00-30A provides discussion and recommendations that provide

information on avoiding or minimising encounters with CAT.

9. FAA Advisory Circular 00-30A

9.1 Introduction

Describes various types of CAT.

Some weather patterns associated with CAT.

Rules of thumb for avoiding or minimising.

Encounters with CAT.

Although based on Northern Hemisphere conditions, the information applies equally to

Southern Hemisphere.

9.2 PURPOSE

This advisory circular (AC) describes to pilots, aircrew members, dispatchers, and other

operations personnel the various types of clear air turbulence (CAT) and some of the

weather patterns associated with it, and provides the "Rules of Thumb" for avoiding or

minimizing encounters with CAT.

CANCELLATION.

This revision supersedes AC 00-30, Rules of Thumb for Avoiding or Minimizing Encounters

With Clear Air Turbulence, dated March 5, 1970.

9.3 BACKGROUND

In 1966, the National Committee for Clear Air Turbulence officially defined CAT as "all

turbulence in the free atmosphere of interest in aerospace operations that is not in or

adjacent to visible convective activity (this includes turbulence found in cirrus clouds not in or

adjacent to visible convective activity)." Over time, less formal definitions of CAT have

evolved. Advisory Circular 00-45C, Aviation Weather Services, defines CAT as "high level


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turbulence (normally above 15,000 feet AGL) not associated with cumuliform cloudiness,

including thunderstorms." The Airman's Information Manual expands on the basic AC 00-

45C CAT definition as "turbulence encountered in air where no clouds are present. This term

is commonly applied to high level turbulence associated with windshear. Thus, clear air

turbulence or CAT has been defined in several ways, but the most comprehensive definition

is: "turbulence encountered outside of convective clouds." This includes turbulence in cirrus

clouds, within and in the vicinity of standing lenticular clouds and, in some cases, in clear air

in the vicinity of thunderstorms. Generally, though, CAT definitions exclude turbulence

caused by thunderstorms, low altitude temperature inversions, thermals, or local terrain

features.

CAT was recognized as a problem with the advent of multiengine jet aircraft in the 1950s.

CAT is especially troublesome because it is often encountered unexpectedly and frequently

without visual clues to warn pilots of the hazard.

9.4 DISCUSSION

One of the principal areas where CAT is found is in the vicinity of the jetstream or jetstreams.

A jetstream is a river of high altitude wind with a speed of 50 knots, or greater, following the

planetary atmospheric wave pattern. There are, in fact, three jetstreams: the polar front

jetstream, the subtropical jetstream, and the polar night jetstream. The polar front jetstream

as its name implies, is associated with the polar front or the division between the cold polar

and warm tropical air masses. The mean latitude of the jetstream core varies from 25 north

latitude during the winter months to 42 north latitude during the summer months.

The polar front jetstream is the centre of the planetary wave pattern and as such meanders

over a large portion of the hemisphere throughout the year, particularly during the winter

months when it is most intense. Although the polar front jetstream varies in altitude, the core

is most commonly found around 30,000 feet and it is generally best depicted on the 300millibar constant pressure map.

The subtropical jetstream is a very persistent circumpolar jetstream found on the northern

periphery of the tropical latitudes between 20 and 30 north latitude. It normally forms three

waves around the globe with crests over the eastern coasts of Asia and North America and

the Near East. Like the polar front jetstream, the subtropical jetstream is most active during

the winter months and often intrudes well into the southeastern United States. It is generally

higher than the polar front jetstream with the core between 35,000 and 45,000 feet.


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The polar night jetstream is found in the stratosphere in the vicinity of the Arctic Circle during

the winter months and does not have a significant affect on air travel over the United States

and southern Canada.

CAT associated with a jetstream is most commonly found in the vicinity of the tropopause

and upper fronts. The tropopause is actually an upper front separating the troposphere from

the stratosphere. Analyses of the tropopause are issued by the National Weather Service on

a scheduled basis. In the absence of other information, the tropopause will generally have a

temperature of between -55 C. and -65 C. In some cases, it will be at the top of a cirrus

cloud layer. Clouds are very seldom found above the tropopause in the dry stratosphere,

except in the summertime when occasionally large thunderstorms will poke through the

tropopause and spread anvil clouds in the stratosphere. CAT is most frequently found on the

poleward side of the jetstream (the left side facing downwind). It is additionally common in

the vicinity of a jetstream maxima (an area of stronger winds that moves along the

jetstream).

There are several patterns of upper level winds that are associated with CAT. One of these

is a deep, upper trough. The CAT is found most frequently at and just upwind of the base of

the trough, particularly just downwind of an area of strong temperature advection. Another

area of the trough in which to suspect CAT is along the centerline of a trough where there is

a strong horizontal windshear between the northerly and southerly flows. CAT is also found

in the back side of a trough in the vicinity of a wind maxima as the maxima passes through.

One noteworthy generator of CAT is the confluence of two jetstreams. On occasion, the

polar front jetstream will dip south and pass under the subtropical jetstream. The area of

windshear between the two jetstreams in the area of confluence and immediately

downstream is frequently turbulent.

CAT is very difficult to predict accurately, due in part to the fact that CAT is spotty in both

dimensions and time. Common dimensions of a turbulent area associated with a jetstream

are on the order of 100 to 300 miles long, elongated in the direction of the wind, 50 to 100

miles wide, and 2,000 to 5,000 feet deep. These areas may persist from 30 minutes to a

day. In spite of the difficulty forecasting CAT, there are rules that have been developed to

indicate those areas where CAT formation is likely.

The threshold windspeed in the jetstream for CAT is generally considered to be 110 knots.

Windspeed in jetstreams can be much stronger than 110 knots and the probability of


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encountering CAT increases with the windspeed and the windshear it generates. It is not the

windspeed itself that causes CAT; it is the windshear or difference in windspeed from one

point to another that causes the wave motion or overturning in the atmosphere that is

turbulence to an aircraft. Windshear occurs in all directions, but for convenience it is

measured along vertical and horizontal axes, thus becoming horizontal and vertical

windshear. Moderate CAT is considered likely when the vertical windshear is 5 knots per

1,000 feet, or greater, and/or the horizontal windshear is 20 knots per 150 nautical miles, or

greater. Severe CAT is considered likely when the vertical windshear is 6 knots per 1,000

feet and/or the horizontal windshear is 40 knots per 150 miles or greater.

Until practical airborne detectors are developed, pilots are urged to use the "Rules of Thumb

to Assist in Avoiding or Minimizing Encounters With Clear Air Turbulence" contained in

Appendix 1. The majority of these guidelines were developed initially by the International

Civil Aviation Organization's (ICAO) Sixth Air Navigation Conference of April/May 1969, but

have been expanded based on recommendations from the Department of Defense, the

National Transportation Safety Board, and the Federal Aviation Administration.

9.5 RECOMMENDATION

All pilots and other personnel concerned with flight planning should carefully consider the

hazards associated with flight through areas where pilot reports or aviation weather

forecasts indicate the presence of CAT including mountain wave turbulence. The Rules of

Thumb in Appendix 1 are intended to assist pilots in avoiding potentially hazardous CAT

during flight.

9.6 SUMMARY

Definition of CAT: Turbulence encountered outside of convective clouds

Definition of Jetstream: A river of high altitude wind a speed of 50 knots or greater

following the planetary atmospheric wave pattern. Three types of Jetstreams

1. Polar Front

2. Subtropical

3. Polar Night

The most common areas of Turbulence associated with Jetstreams greater than 110

knots are:

1. Poleward side of Jestream.

2. At the core (Jetstream Maxima).

3. Between 2 Jetstreams in area of confluence and downstream of that area.


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4. Where a vertical windshear of > 5 knots / 1000 feet or 20 knots over 100nm

horizontally exists.

5. In a sloping tropopause above the Jetstream.

6. In the Jetstream front below the core.

7. On the low pressure side of the core.


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10. LIST OF MANUAL REFERENCES

Listed below are some relevant reference material related to Turbulence Penetration for

each aircraft type. Every effort has been made to ensure these lists are current on date of

printing. Please update your references as amendments are released.

10.1 List of Manual References for 747 400

Source Key words Page Amendment

FCTM Reduced Thrust Takeoff, potentialwindshear conditions

01.23 01 Apr 1999

FCTM Windshear 01.27 01 Apr 1999

FCTM Windshear / GPWS 01.30 01 Apr 1999

FCTM Turbulent Air Penetration 01.31 01 Apr 1999

FCTM Cruise-Altitude Selection 02.21 01 Apr 1999

FCTM High Speed Descent 02.35 01 Apr 1999

FCTM Rapid Descent, Entry & Level Off 02.39 01 Apr 1999

FCTM Holding 02.42 01 Apr 1999

FCTM Reference Ground Speed 02.65 01 Apr 1999

FCTM Final Approach, wind correction 03.13 01 Apr 1999

FCTM Radar Operating Techniques 04.33-38 01 Apr 1999

OPS Manual Engine Continuous Ignition GE SP.7.1 05 Oct 2000

OPS Manual RVSM Contingency Procedures SP.11.10 30 Apr 2000

OPS Manual Turbulence SP.16.15 22 Dec 2000

QRH Windshear NNM.1.9 01 Nov 2000

OPS Manual 2 Automatic Flight Windshear Recovery

4.20.16 11 Feb 2000

OPS Manual 2 Predictive Windshear 15.10.12 30 Apr 2000OPS Manual 2 Windshear Alerts 15.20.16 30 Apr 2000

PerformanceLimitations RR

Severe Turbulent Air Penetration 1-3-5 01 Jul 1998

PerformanceLimitations GE

Engine Ignition 1-1-4 20 Oct 2000

PerformanceLimitations GE

Severe Turbulent Air Penetration 1-3-5 11 Mar 2000

PerformancePlanning RR

Nav/Log - Shear Rate 1-9-18 20 Jun 2000

Performance

Planning GE

Nav/Log - Shear Rate 1-9-18 20 Jun 2000

FAM Crew Safety Harnesses & SeatBelts

7-4 3 Oct 2000

FAM Seat Belts & Illumination of Signs 8-9 3 Oct 2000

FAM Wake Turbulence Pilot Waivers 9-19 23 Aug 2000

FAM Turbulence Reporting, TurbulenceReporting Criteria Table

20(s)-4 &-5

1 May 1999

Flying Manual Windshear & Flight Planning 11-1 Apr 30/96


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10.2 List of Manual References for 747-2/3/SP


747 FCTM Turbulent Air Penetration 02.20.03 16 Jan 1998

747 FCTM Cruise Turbulence 02.30.01 18 Feb 1994

747 FCTM Descent (FRATS) 03.20.02 26 Oct 1998

747 FCTM FFRATS Approach Procedures 03.20.02 26 Oct 1998747 FCTM Turbulence during descent 03.30.02 01 Mar 1995

747 FCTM Turbulence during holding 03.30.03 18 Feb 1994

FCTM Windshear 01.10.16,01.10.17&01.10.18

18 Feb 1994

747B RR-Performance Manual

Severe Turbulent Air Penetration 2-2-12 01 Sep 1999


Approx N1% Thrust Setting 2-2-12 01 Sep 1999


Weather Radar With TurbulenceDisplay (338 only)

2-1-8 14 Jan 1991


Engine Ignition 2-1-7 28 Sep 1992


FFRATS 2-1-13 14 Jan 1991

747-2/3/SPOperations Manual

Limitations Summary 01.10.01 05 Dec 2000


Severe Turbulence 02.30.16&02.30.17

24 May 2000

747-2/3/SP

Operations Manual

Power Plant Use of Ignition 02.43.01 15 Jan 1996


Autopilot/Flight Director ModeSelector

07.10.05 23 Dec 1999


Turbulence 07.30.02 13 Jun 1998


Weather Radar 19.10.09 01 Apr 1994

FAM Crew Safety Harnesses & SeatBelts

7-4 03 Oct 2000

FAM Seat Belts and Illumination of Signs

8-9 03 Oct 2000

FAM Wake Turbulence Pilot Waivers 9-19 23 Aug 2000FAM Turbulence Reporting, Turbulence

Reporting Criteria Table20(S)-4& 20(S)-5

01 May 1999

Flight Operations Flying Manual

Windshear and Flight Planning 11-1 30 Apr 1996


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10.3 List of Manual References for 767


767 OperationsManual

Turbulence Preface0.3.6

29 Jul 2000

767 Operations

Manual

Turbulence/Severe Turbulence SP 16.8 2 Jan 2001


WX+T 11.10.19 29 Jul 2000


WX/Turbulence11.Supp.2

29 Jul 2000

FCTM Turbulence Penetration 1-65 29 Feb 2000

FCTM Turbulence Penetration CorrectProcedures

1-70 29 Feb 2000

FCTM Turbulence Penetration Discussion Items

Manylesson

plansFCTM Turbulence Penetration01.10.09/10

23 Aug 1993

FAM CABINMANAGEMENT

Seat Belt Signs Turbulence(anticipated/unanticipated)

FAM Turbulence Reporting 20(S)-4 01 May 99

FAM Wearing of Seat Belts 7-4 03 Oct 2000

FAM Seat Belt Wearing of 8-9/10 20 Dec 2000

767 RR PerformanceLimitations

Severe Turbulence Penetration 1-1-6 15 Jun 2000

767-338

PerformancePlanning

Severe Turbulence Air Penetration 6.1.1 24 Jan 1992

767-338PerformanceLimitations

Severe Turbulence Air Penetration 1.1.6 5 May 1999

767-238PerformancePlanning

Severe Turbulence Air Penetration 6.1.1 24 Jan 1992

767-238PerformanceLimitations

Severe Turbulence Air Penetration 1.1.6 30 Aug 2000

Flying Manual Climbing with anticipatedturbulence 5-14 01 Apr 1995

Flying Manual Radar returns of turbulence 6-2/3 01 Apr 1995

Flying Manual Doppler Turbulence Mode 6-4 01 Apr 1995


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10.4 List of Manual References for 737


737 FCTM Landing 1.10 01 Feb 2000

737 FCTM Turbulent Air Penetration 1.18 01 Feb 2000

737 FCTM Windshear 1.20 01 Feb 2000

737 FCTM Optimum Altitude 3.4 01 Feb 2000737 FCTM Holding 4.1 01 Feb 2000

737 FCTM Rapid Descent 5.14 01 Feb 2000

737 OperationsManual, Volume 1

Operational Limitations L.10.3 30 Jun 2000


Approach Procedure NP.20.33 30 Sep 2000


Turbulence SP.16.15 22 Dec 2000


Windshear SP.16.16 22 Dec 2000


Weather Radar 11.20.7 30 Oct 1999

737 OperationsManual, Volume 3(-300)

Turbulent Air Penetration 23.30.03 7/86

737 OperationsManual, Volume 3(-400)

Turbulent Air Penetration 24.30.03 2/90


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11. APPENDIX 1

Rules of Thumb to assist in avoiding or minimizing encounter with clear air

turbulence

NOTE: The following Rules of Thumb apply primarily to the westerly jetstreams.

Jetstreams stronger than 110 knots (at the core) are apt to have areas of significant

turbulence near them in the sloping tropopause above the core, in the jetstream front below

the core, and on the low pressure side of the core. Windshear and its accompanying CAT in

jetstreams is more intense above and to the lee of mountain ranges. CAT should be

anticipated whenever the flightpath traverses a strong jetstream in the vicinity of

mountainous terrain. Both vertical and horizontal windshear are, of course, greatly intensified

in mountain wave conditions. Therefore, when the flightpath traverses a mountain wave type

of flow, it is desirable to fly at turbulence penetration speed and avoid flight over areas where

the terrain drops abruptly, even though there may be no lenticular clouds to identify the

condition. On charts for standard isobaric surfaces, such as 300 millibars, if 20 knot isotachs

are spaced closer together than 150 nautical miles (2 degrees latitude), there is sufficient

horizontal shear for CAT. This area is normally on the poleward (low pressure) side of the

jetstream axis, but in unusual cases may occur on the equatorial side. Turbulence is also

related to vertical shear. From the tropopause height/vertical windshear chart, determine the

vertical shear in knots per thousand feet. If it is greater than 5 knots per 1,000 feet,

turbulence is likely. Curving jetstreams are more apt to have turbulent edges than straight

ones, especially jetstreams which curve around a deep pressure trough. Wind shift areas

associated with pressure troughs and ridges are frequently turbulent. The magnitude of the

windshear is the important factor. If jetstream turbulence is encountered with direct tailwinds

or headwinds, a change of flight level or course should be initiated since these turbulent

areas are elongated with the wind and are shallow and narrow. If jetstream turbulence is

encountered in a crosswind, it is not so important to change course or flight level since the

rough areas are narrow across the wind. If turbulence is encountered in an abrupt wind shift

associated with a sharp pressure trough line, establish a course across the trough rather

than parallel to it. If turbulence is expected because of penetration of a sloping tropopause,

watch the temperature gauge. The point of coldest temperature along the flightpath will be

the tropopause penetration. Turbulence will be most pronounced in the temperature change

zone on the stratospheric (upper) side of the sloping tropopause. If possible, when crossing

the jet, climb with a rising temperature and descend with a dropping temperature. Weathersatellite pictures are useful in identifying jetstreams associated with cirrus cloud bands. CAT


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is normally expected in the vicinity of jetstreams. Satellite imagery showing wavelike or

herringbone cloud patterns are often associated with mountain wave turbulence. Pilots

should avail themselves of briefings on satellite data whenever possible. Last, but not least,

monitor your radio pilot reports can be invaluable and if you get caught by the CAT, file a

PIREP! NOTE: In this country, civil forecasts of areas of CAT are made by the National

Weather Service and disseminated as follows: (1) in area forecasts every 8 hours (every 6

hours in Hawaii); (2) on high level significant weather facsimile charts available every 6

hours, and (3) on a nonscheduled basis as inflight advisories (SIGMETS). SIGMETS are

issued when severe or extreme CAT is forecast or has been reported. This information is

available to pilots through the enroute advisory service (flight watch), in SIGMET alerts

broadcast on air route traffic control centre frequencies, and over the hazardous inflight

weather advisory service (HIWAS).


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12. BIBLIOGRAPHY

Federal Aviation Administration, 1998, FAA Advisory Circular 00-30A, Federal

Aviation Administration, United States of America

Qantas Flight Publications, 2001,Aircrew Emergency Procedures Manual, Qantas Ltd,

Australia

Qantas Flight Publications, 2001, 747 Flight Crew Training Manual, Qantas Ltd,

Australia


Australia


Australia

Qantas Flight Publications, 2001, 737 Flight Crew Training Manual, Volume 1, Qantas

Ltd, Australia


Ltd, Australia


Ltd, Australia

Qantas Flight Publications, 2001, Performance 747B RR, Qantas Ltd, Australia

Qantas Flight Publications, 2001, 747-2/3/SP Operations Manual, Qantas Ltd,

Australia Qantas Flight Publications, 2001, 744 Operations Manual, Qantas Ltd, Australia

Qantas Flight Publications, 2001, 767 Operations Manual, Qantas Ltd, Australia

Qantas Flight Publications, 2001, 737 Operations Manual, Qantas Ltd, Australia

Qantas Flight Publications, 2001, Flight Administration Manual, Qantas Ltd, Australia

Qantas Flight Publications, 2001, 744 Performance Limitations RR,Qantas Ltd,

Australia

Qantas Flight Publications, 2001, 767 RR Performance Limitations,Qantas Ltd,

Australia

Qantas Flight Publications, 2001, 767-338 Performance Planning,Qantas Ltd,

Australia

Qantas Flight Publications, 2001, 767-338 Performance Limitations,Qantas Ltd,

Australia

Qantas Flight Publications, 2001, Flying Manual,Qantas Ltd, Australia

Qantas Flight Publications, 2001, 744 Performance Limitations GE,Qantas Ltd,

Australia

Qantas Flight Publications, 2001, 744 Performance Planning GE,Qantas Ltd, Australia


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Turbulence Penetration Procedures Co-ordinated Briefing, Issue 1 Page 18 of 18

Version Date Authorised by Changes

1 28/7/06 B McAlpine Delete out of date references to AEPM

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Turbulence Penetration